Karlseifertite, Pb(Ga₂Ge)(AsO₄)₂(OH)₆, a new dussertite-group mineral, from Tsumeb, Namibia
- Creators
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Kampf, Anthony R.1
- Désor, Joy2
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Ma, Chi3
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1.
Natural History Museum of Los Angeles County
- 2. Im Langenfeld 4, 61350 Bad Homburg, Germany
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3.
California Institute of Technology
Abstract
Karlseifertite (IMA 2024-007, International Mineralogical Association), Pb(Ga2Ge)(AsO4)2(OH)6, is a new member of the dussertite group, from Tsumeb, Namibia. It is a secondary oxidation-zone mineral found on fracture surfaces in germanite–chalcocite ore. Karlseifertite occurs in rosettes of thin, yellow, hexagonal plates up to about 0.2 mm in diameter and usually less than 0.01 mm thick. The mineral has a pale-yellow streak, subadamantine lustre, Mohs hardness of ∼ 4, brittle tenacity, irregular fracture, perfect cleavage on {001} and a calculated density of 4.993 g cm−3. Optically, karlseifertite crystals are uniaxial (+), with ω=1.890(5) and ε=1.894(calc) (white light). The empirical formula from electron probe microanalyses is Pb(GaGeFeAl)Σ2.97[(AsSW)Σ1.00O4]2(OH0.99)6. Karlseifertite is trigonal with space group and unit-cell parameters a=7.2814(7), c=17.1077(12) Å, V=785.50(15) Å3 and Z=3. The mineral has an alunite-supergroup structure (R1=0.0591 for 248 reflections with I>2σI).
Copyright and License
© Author(s) 2024. This work is distributed under the Creative Commons Attribution 4.0 License.
Acknowledgement
Reviewers Jochen Schlüter and Oleg Siidra are thanked for their constructive comments on the paper.
Funding
A portion of this study was funded by the John Jago Trelawney Endowment to the Mineral Sciences Department of the Natural History Museum of Los Angeles County.
Contributions
ARK oversaw the research, determined the physical and optical properties, did the Raman spectroscopy, did the X-ray diffraction studies and wrote the paper. JD conducted initial characterization studies on the mineral and identified it as a potentially new species. CM did the electron microprobe analyses.
Data Availability
Crystallographic data for karlseifertite are available in the Supplement.
Supplemental Material
The supplement related to this article is available online at: https://doi.org/10.5194/ejm-36-873-2024-supplement.
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Additional details
- Natural History Museum of Los Angeles County
- John Jago Trelawney Endowment -
- Accepted
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2024-08-14Accepted
- Caltech groups
- Division of Geological and Planetary Sciences
- Publication Status
- Published